EP4698862A1

EP4698862A1 - Multispectral optical sensor and manufacturing method thereof

Info

Publication number: EP4698862A1
Application number: EP24717143.2A
Authority: EP
Inventors: Gunter Siess; Mohsen Mozaffari
Original assignee: Ams Sensors Germany GmbH
Current assignee: Ams Sensors Germany GmbH
Priority date: 2023-04-21
Filing date: 2024-04-02
Publication date: 2026-02-25
Also published as: WO2024217862A1; CN120530304A

Abstract

A multispectral optical sensor comprises a monolithic semiconductor chip (510, 810) defining a plurality of subarrays (512, 812) of optical detector regions (511, 811), each subarray comprising the same number and relative spatial arrangement of optical detector regions (511, 811); a plurality of lens arrangements, each of which is corresponding to one of the plurality of subarrays (512, 812); wherein each lens arrangement comprises an upper lens arrangement having an upper convex lens element (570a, 870a, 970a), and a lower lens arrangement having a lower convex lens element (570b, 870b, 970b) and a bottom glass substrate (571c, 871d, 971c) mounted on the monolithic semiconductor chip (510, 810) through its bottom surface; wherein each lens arrangement further comprises an optical filter (566, 866, 966) provided on top surface of the bottom glass substrate (571c, 871d, 971c), so that incident light from a scene passes through the optical filter (566, 866, 966) and then propagates in the bottom glass substrate (571c, 871d, 971c) along a direction towards a detector region (511, 811) of a subarray (512, 812) corresponding to the optical filter (566, 866, 966).

Description

MULTISPECTRAL OPTICAL SENSOR AND MANUFACTURING METHOD THEREOF

The present disclosure relates to a multispectral optical sensor, in particular to a multispectral optical sensor with an interference filter layer within its MLA stack. The present invention also relates to a method of manufacturing the multispectral optical sensor.

BACKGROUND OF THE INVENTION

Color constancy is a desirable attribute of image-sensing devices, such as cameras. Color constancy refers to a capability of observing a feature or object as being of a relatively constant color under different illuminations. That is, an appearance of an image captured by a camera may be affected by an ambient illumination. By means of example, if a color temperature of an ambient light source is relatively low, e.g. in the region of 3000 Kelvin as may be the case for an incandescent light source, an image of a white object exposed to the ambient light source will comprise a reddish hue. In contrast, for an ambient light source with a high color temperature, e.g. in the region of 6000 Kelvin as may be the case for daylight on an overcast day, the image of the white object will comprise a slight blueish hue. That is, the object will be observed by a camera as comprising a color that depends upon the illumination of the object by the ambient light source.

It is known to compensate for such effects by using a multispectral ambient light sensor (ALS) to measure spectral information relating to a scene . For example , with reference initially to Fig . 1A, there is shown a smartphone 101 including a multi-spectral optical sensor arrangement in the form of a multi-spectral ALS arrangement 103 , a camera 104 having a known spatial relationship relative to the ALS arrangement 103 , and a cover glass 108 which covers the multi-spectral ALS arrangement 103 and the camera 104 . FIG . IB shows a detailed cross-sectional view of the multi- spectral ALS arrangement 103 and the camera 104 . The multi- spectral ALS arrangement 103 includes a multi-spectral ALS

102 having a plurality of optical detector regions 111 . In the interests of clarity, only three optical detector regions 111 are shown in FIG . IB . However, the multi-spectral ALS 102 actually defines more than three optical detector regions 111 . The multi-spectral ALS arrangement 103 includes a housing 120 which houses the multi-spectral ALS 102 . The multi-spectral ALS arrangement 103 further includes an IR cut filter 132 located between the cover glass 108 and the housing 120 . The housing 120 defines an aperture or a window 122 for admitting light into the housing 120 via the cover glass 108 and the IR cut filter 132 . The multi-spectral ALS arrangement 103 has an optical axis 140 which is normal to a front surface of the multi-spectral ALS 102 . The multi- spectral ALS arrangement 103 is configured to discriminate between light incident on the multi-spectral ALS arrangement

103 from a scene along di f ferent directions of incidence and to measure the spectral distribution of the light incident on the multi-spectral ALS arrangement 103 for the di f ferent directions of incidence across a FOV 142 which defines a solid angle around the optical axis 140 of the multi-spectral ALS arrangement 103 . Speci fically, the multi-spectral ALS arrangement 103 is configured to discriminate between light incident on the multi-spectral ALS arrangement 103 from di f ferent sectors 142a, 142b, ... 142 i of the FOV 142 and to measure the spectral distribution of the light incident on the multi-spectral ALS arrangement 103 from each sector 142a, 142b, ... 142 i . The camera 104 also has an optical axis 150 which is normal to a front surface of an image sensor chip (not shown) of the camera 104 and which is parallel to the optical axis 140 of the multi-spectral ALS arrangement 103 . The camera 104 has a FOV 152 which defines a solid angle around the optical axis 150 of the camera 104 , wherein the solid angle of the FOV 152 of the camera 104 is comparable to the solid angle of the FOV 142 of the multi-spectral ALS arrangement 103 .

FIG . 2 illustrates a schematic of a multi-spectral ALS shown in FIG . 1 . The multi-spectral ALS 102 includes an aperture member 160 defining a plurality of apertures 160a, a first microlens array (MLA) 161a, a second microlens array (MLA) 161b, a monolithic multi-spectral ALS semiconductor chip 110 , a PCB 162 and a frame member 164 . The monolithic multi- spectral ALS semiconductor chip 110 and the frame member 164 are mounted on the PCB 162 with the frame member 164 located around the monolithic multi-spectral ALS semiconductor chip 110 . The PCB 162 and the frame member 164 together form the housing 120 which holds the aperture member 160 , and the first and second MLAs 161a, 161b in alignment with the monolithic multi-spectral ALS semiconductor chip 110 .

The monolithic multi-spectral ALS semiconductor chip 110 also includes a plurality of optical filters 166 formed on, or attached to , the monolithic multi-spectral ALS semiconductor chip 110 . So that , each optical filter 166 is arranged in front of a corresponding sub-array 112 of optical detector regions 111 and has a corresponding optical transmission spectrum . Speci fically, each optical filter 166 is a passband optical interference filter which defines a corresponding spectral passband . Di f ferent optical filters 166 may, for example define di f ferent spectral passbands .

The multi-spectral ALS 102 comprises a plurality of lens arrangements 370 , one of which is shown in FIG . 3 . The lens arrangement 370 has an upper lens arrangement comprising a convex lens element 370a, and a lower lens arrangement comprising a convex lens element 370b . The two convex lens elements 370a and 370b are disposed towards each other . The upper convex lens element 370a is formed on the upper glass stack comprising a first glass wafer 371a and a second glass wafer 371b . Two apertures 360a, 360b are formed within the upper lens arrangement . The first aperture 360a is implemented between the first glass wafer 371a and the second glass wafer 371b, which restricts the light entering the second glass wafer 371b from the first glass wafer 371a . The second aperture 360b is implemented between the second glass wafer 371b and the upper convex lens element 370a, which is the entrance aperture of the upper convex lens element 370a . The lower lens arrangement comprises a third glass wafer 371c and the lower convex lens element 370b formed on the third glass wafer 371c . The third aperture 360c, i . e . the exit aperture of the lower convex lens element 370b, is implemented between the lower convex lens element 370b and the third glass wafer 317c . The apertures are formed by, e . g . applying an opaque coating or an opaque film/ foil on the surface of the glass wafer .

An optical filter 366 is positioned between the lens arrangement 370 , or more speci fically, the lower lens arrangement of the lens arrangement 370 and a corresponding detector subarray 312 . So that , light from a scene incident on this lens arrangements 370 propagates through the first glass wafer 371a, the second glass wafer 371b, the upper convex lens element 370a, the lower convex lens element 370b and the third glass wafer 371c, and then through the corresponding optical filter 366 towards di f ferent optical detector regions 311 of the corresponding subarray 312 depending on the directions of incidence . The incident light shown in Fig . 3 is focused on the plane of the optical detector regions 311 . It is also possible that , the incident light forms an out-of- focus image of the scene at a plane of the optical detector regions to reali ze blur ef fect .

FIG . 3 shows that , an optical interference filter 366 is aligned between a corresponding lens arrangement 370 and a corresponding sub-array 312 of optical detector regions 311 . The plurality of interference filters 366 or the interference filter layer is directly formed or attached to a passivation layer 368 covering the surface of the Si wafer of the chip 310 . Of course , the material is not limited to silicon . Semiconductor chip 310 may have a wafer made of a material other than silicon . So that , each of the optical filters 366 is in front of a corresponding subarray 312 on the monolithic multi-spectral ALS semiconductor chip 310 . The lens arrangement 370 is mounted on the chip 310 , or more specially, on the passivation layer 368 through optical glue 367 .

Each optical filter 366 is a passband optical interference filter which defines a certain spectral passband and is configured to only transmit a certain range of wavelengths onto a corresponding subarray 312 . Two or more of the optical filters 366 may define di f ferent spectral passbands . The main problem of processing an interference filter layer directly on the Si wafer of the chip 310 is the significant interference ripples in low field of view, which is caused by the thickness of passivation layer 368. In the prior art shown in Figure 3, the interference distance of the effective mirror is the distance between the bottom H layer of the optical filter 366 and the Si wafer of the chip 310, which is determined by the thickness of the passivation layer 368, typically 6-9 pm. This small interference distance leads to a lot of interference ripples in the transmission spectrum of the interference optical filter 366, especially within the low field of view. In addition, any change in the thickness of the passivation layer 368 will result in a phase shift of the ripples.

FIG. 4 (a) illustrates the ideal optical transmission spectrum of an interference optical filter 366 as arranged in Fig. 3 and the obtained actual optical transmission spectrum of the interference optical filter 366 is shown in FIG 4 (b) . The actual spectrum shows that interference ripples are formed. As mentioned above, optical transmission spectra of interference optical filters for the same spectral channel of different multispectral ambient light sensors will have different ripples due to the variation of passivation layer thicknesses in different sensors. This means that the spectral sensitivity of each sensor for the same channel will have a different shape and cannot reach the designed spectrum shown in Figure 4 (a) . Especially for a sectored view multi spectral sensor, which limits the FOV to a small angle, e.g. <10 degrees, the ripples can significantly affect the spectral sensitivity. Another problem with processing interference filters directly on the silicon wafer is the required mechanical stress during filter layer processing . To prevent signi ficant warpage , the bottom glass wafer needs to have the minimum thickness for processing the filter . Typically, a thickness of at least 900pm is recommended . Thee filter layer is processed on the bottom surface of the glass wafer, which is to be mounted on a monolithic semiconductor chip, and the top layer of the glass wafer is molded with lens structure . Therefore , it is not possible to reduce the thickness of the bottom glass wafer, nor can it be reduced during the wafer-scale stacking process . Thus , the prior art multispectral optical sensor cannot have a thin structure .

An obj ect to be achieved is to provide a multispectral optical sensor with reduced thickness , and the same time with an improved optical transmission spectrum . A further obj ect is to provide a method of manufacturing such multispectral optical sensor .

These obj ects are achieved with the subj ect-matter of the independent claims . Further developments and embodiments are described in dependent claims .

SUMMARY OF THE INVENTION

The improved concept is based on the idea of providing a multispectral optical sensor comprising a monolithic semiconductor chip defining a plurality of subarrays of optical detector regions , each subarray comprising the same number and relative spatial arrangement of optical detector regions ; a plurality of lens arrangements , each of which is corresponding to one of the plurality of subarrays ; wherein each lens arrangement comprises an upper lens arrangement having an upper convex lens element , and a lower lens arrangement having a lower convex lens element and a bottom glass substrate mounted on the monolithic semiconductor chip through its bottom surface ; wherein each lens arrangement further comprises an optical filter provided on top surface of the bottom glass substrate , so that incident light from a scene passes through the optical filter and then propagates in the bottom glass substrate along a direction towards a detector region of a subarray corresponding to the optical filter . The monolithic semiconductor chip may be a Si chip, but not limited to Si chip . The incident light may be UV light , VIS light , NIR light or SWIR light .

Preferably, each lens arrangement is aligned to focus the incident light onto a focal plane at the plane of the subarray of optical detector regions to form a focused image at the plane of the subarray of optical detector regions .

This may be achieved by designing the thickness of the bottom glass substrate .

Preferably, each lens arrangement is aligned to focus the incident light onto a focal plane adj acent the plane of the subarray of optical detector regions to form an out-of- focus image at the plane of the subarray of optical detector regions . Thus , blur ef fect can be achieved .

Preferably, the optical filter is sandwiched between the lower convex lens element and the bottom glass substrate . Thus , the optical filter is located at the exit aperture of the lower convex lens element . Preferably, the lens arrangement further comprises an additional glass substrate , which is placed between the lower convex lens element and the optical filter . Then, an additional aperture is formed between the additional glass substrate and the bottom glass substrate . The optical filter is arranged at the location of the additional aperture .

Preferably, the upper lens arrangement further comprises a first glass substrate , and also a second glass substrate on which upper convex lens element are arranged .

Preferably, a passivation layer is arranged on top of the monolithic semiconductor chip . The passivation layer is typically 6- 9 pm .

Preferably, the upper convex lens element is a micro lens or a micro-Fresnel lens . The lower convex lens element is also a micro lens or a micro-Fresnel lens .

Preferably, the thickness of the bottom glass substrate is 200-400 pm . This thickness can be achieved by grinding the initial bottom glass substrate with a thickness of 900 pm .

The improved concept is also based on the idea of providing a method of manufacturing a multispectral optical sensor, comprising the steps of processing a structured optical filter layer on top surface of a bottom glass substrate/glass wafer, molding a lower layer of MLA on top of the structured optical filter layer, mounting a plurality of baf fle structures/ spacers onto the top surface of the bottom glass substrate/glass wafer, and mounting an upper lens arrangement layer comprising an upper glass substrate/glass wafer and an upper layer of MLA to the bottom glass substrate/glass wafer, so that the upper layer of MLA and the bottom layer of MLA are faced to each other . The step of mounting the upper lens arrangement layer is state of the art . The upper lens arrangement layer may have a first glass substrate , and also a second glass substrate on which upper convex lens element are arranged .

Preferably, the method further comprises grinding the bottom glass substrate/glass wafer to a predetermined thickness from its bottom surface to form a structure comprising plurality of lens arrangements .

Preferably, the predetermined thickness is 200-400 pm . The thickness is designed to achieve a focused image or an out-of - focus image at the plane of the subarray of optical detector regions .

Preferably, the method further comprises dicing the structure to a plurality of separated lens arrangements and attach the lens arrangements to the monolithic semiconductor chip .

Further embodiments of the method become apparent to the skilled reader from the embodiments of the multispectral optical sensor described above , and vice-versa .

BRIEF DESCRIPTION OF THE DRAWINGS

The following description of figures may further illustrate and explain aspects of the multispectral optical sensor and the manufacturing .

DETAILED DESCRIPTION In the figures :

Fig . 1A is a schematic of a rear side of an electronic device in the form of a smartphone having a multi-spectral ALS arrangement and a camera ;

Fig . IB is a schematic cross-section of the multi-spectral ALS arrangement and the camera of the smartphone of FIG . 1A;

Fig . 2 is a schematic of a prior art multi- spectral ALS ;

Fig . 3 is a schematic of lens arrangement of a spectral channel of the multi-spectral ALS of Figure 2 ;

Figs . 4 ( a ) and (b ) illustrate the ideal optical transmission spectrum and the actual optical transmission spectrum of the interference optical filter in the lens arrangement of FIG . 3 , respectively;

Fig . 5 is a schematic of lens arrangement of a multi-spectral ALS according to an embodiment of the present invention;

Figs . 6 ( a ) and (b ) illustrate the ideal optical transmission spectrum and the actual optical transmission spectrum of the interference optical filter in the lens arrangement of FIG . 5 , respectively;

Fig . 7 illustrates the angular distribution of received light at a multi-spectral ALS according to the present invention;

Fig . 8 is a schematic of lens arrangement of a multi-spectral ALS according to another embodiment of the present invention; Fig . 9 illustrates the manuf cturing process of the multi-spectral ALS according to the present invention .

FIG . 5 illustrates a schematic of lens arrangement of a multi-spectral ALS according to an embodiment of the present invention . The lens arrangement 570 is mounted on the monolithic semiconductor chip 510 , which is covered by a passivation layer 568 , through an optical glue layer 567 . Similar to the prior art lens arrangement 370 , the current lens arrangement 570 comprises an upper convex lens element 570a formed on the upper glass stack comprising a first glass wafer 571a and a second glass wafer 571b and a lower convex lens element 570b formed on the third glass wafer 571c . Three apertures 560a, 560b, and 560c are formed between the first and second glass wafers 571a and 571b, between the second glass wafer 571b and the upper convex lens element 570a, and between the lower convex lens element 570b and the third glass wafer 571c, respectively . The optical filter 566 is located at the position of the third aperture 560c . So that , light from a scene incident on any one of the lens arrangements 570 along di f ferent directions of incidence propagates through the first glass wafer 571a, the second glass wafer 571b, the upper convex lens element 570a, and the lower convex lens element 570b . Then light arrived at the third aperture 560c or the exit aperture before the corresponding optical filter 566 . The optical filter 566 is a passband optical interference filter which defines a corresponding spectral passband and is configured to only transmit a corresponding range of wavelengths to the third glass wafer 571c . Light passes through the optical filter 566 propagates within the third glass wafer 571c in di f ferent directions towards the corresponding detector array 512 of optical detector regions 511, as shown in FIG. 5. According to the embodiment shown in FIG. 5, the filtered light is focused on the plane of the optical detector regions 511. It is also possible that, the incident light forms an out-of- focus image of the scene at a plane of the optical detector regions to realize blur effect. By designing the thickness of the third glass wafer 571c, the above mentioned 'in focus' or 'various out of focus' for blur effect can be easily realized.

As mentioned above, the optical filter 566 is positioned at the third aperture 560c, or on top of the third glass wafer 571c. Compared with FIG. 3, the optical filter 566 is moved from the bottom of the third glass wafer 571c to the top of the third glass wafer 571c. So, the interference distance of the effective mirror, which is the distance between the bottom H layer of the optical filter 566 and the Si wafer of the chip 310 will increase from thickness of the passivation layer (6-9 pm) to thickness of the passivation layer plus thickness of the third glass wafer 571c (200-400pm) . The frequency of the resulted interference ripples become very much higher, so that the ripples no longer significantly affect the optical transmission spectrum of the optical filter 566.

Figs. 6 (a) and (b) illustrate the ideal optical transmission spectrum and the actual optical transmission spectrum of the interference optical filter in the lens arrangement of FIG.

5, respectively. The actual optical transmission spectrum of the interference optical filter as arranged according to the present invention is quite close to the ideal optical transmission spectrum, which is a gaussian shape. The ripples generated on the optical transmission spectrum of the interference optical filter are signi ficantly reduced . The spectral range according to the present invention is not limited to the range shown in Figure 6 , it can be also UV, VIS , NIR, SWIR, and etc...

This new approach of implementing the optical filter layer to the MLA stack can prevent additional interference ripples in the transmission that are caused by the passivation layer on the wafer .

As mentioned above , this new design allows for a larger distance between the filter and the detector, and the interference ripple becomes so high in frequency that it is no longer relevant to the filtering application . It reduces the device-to-device variation and greatly increases the performance of the spectral reconstruction .

The lens arrangement according to the present invention has another advantage . The optical filter layer is processes on top of a bottom glass substrate/waf er to be mounted on the monolithic semiconductor chip . Such bottom glass wafer has a high mechanical stress due to the interference filters . So that , this the lower lens arrangement is a stabile substrate for fabricating the upper lens arrange and the lower lens arrangement together .

Figure 7 illustrates the angular distribution of the received light of the multispectral ALS according to the present invention . The curves corresponding to the di f ferent FOVs shown in Fig . 7 all have the same angular distribution . Therefore , the optical filter can be positioned anywhere between the detector array and the lower convex lens element . To achieve the change of position, an additional glass substrate/ layer can be added between the optical filter and the lower convex lens element . This also allows to achieve an additional aperture in the spectral channel .

Figure 8 is a schematic of lens arrangement of a multi- spectral ALS according to another embodiment of the present invention . In this embodiment , an additional glass substrate 871c is added between the lower convex lens element 870b and the fourth glass substrate 871d which is to be mounted on the monolithic semiconductor chip 810 . In this way, position of the optical filter 866 is moved from the exit aperture of the lower convex lens element 870b towards the chip 810 . By designing the thickness of the third glass substrate 871c, the position of the optical filter 866 can be located at any position between detector array 812 and lower convex lens element 870b .

The manufacture process of the above mentioned multispectral optical sensor is illustrated in FIG . 9 . The manufactured optical sensor overcomes the requirement of minimum thickness of the glass sheet due to mechanical stress and warpage .

As shown in Figure 9 ( a ) , the first step of the manufacture process is to process a structured filter layer on an entire thick glass wafer . The thick glass wafer is the bottom glass substrate/waf er which is to be mounted on a monolithic semiconductor chip . Thus , optical filters are distributed on the glass wafer in a certain spatial distribution . The optical transmission spectrum of di f ferent optical filters may be di f ferent . The spectrum may be in the UV range , VIS range , NIR range , SWIR range , and etc... The thickness of this glass wafer is at least 900 pm to meet the mechanical stress requirements when processing the optical filter on the glass substrate/ wafer.

In the next step shown in FIG. 9(b) , a wafer scaled layer of convex lens structures are molded on top of the optical filter layer. So that, each convex lens element is aligned with a corresponding optical filter.

Then, FIG. 9(c) illustrates the step of wafer scaled mount of baffle structure/spacer on the thick glass wafer. The baffle structures/spacers are mounted on the entre thick glass wafer at the required positions for separating another glass wafer in the next step.

A wafer scaled beforehand prepared MLA Array or also an upper lens arrangement as shown in FIG. 5 or 8 is mounted on the MLA array or also the lower lens arrangement as process in the above-mentioned steps. The mounted structure is shown in FIG. 9 (d) .

The following process, as illustrated in FIG. 9 (e) present an advantage of the present invention. Since the wafer scaled optical filter layer is processed on the top side of the glass wafer, the bottom side of the glass wafer is free before being mounted to a monolithic semiconductor chip. Therefore, it is possible to reduce the thickness of the bottom glass wafer to have a thinner sensor structure. So, in this step, the thickness of the bottom glass wafer is reduced by back/bottom grinding to a target thickness. The target thickness is designed to realize the above-mentioned "in focus" or "out of focus" function. The multispectral optical sensor as manufactured according to the method illustrated in FIG. 9 will comprises a plurality of lens arrangements as shown in FIG. 5. To manufacture the lens arrangements as shown in FIG. 8, an additional step of mounting another glass wafer on top of the optical filter layer is added after processing a structured filter layer on the entire thick glass wafer as illustrated in FIG. 9(a) , and before mounting of the wafer scaled baffle structures/spacers as illustrated in FIG. 9(c) . In this embodiment, the thickness of the additional glass wafer may also be designed to help realize the "in focus" or "out of focus" function.

Thus, it is more flexible to design the wafer stack.

In the present manufacture process, the optical filter layer is implemented into MLA stack instead of directly mounted on the Si wafer of the monolithic semiconductor chip. The filter layer processing is conducted on a very stable platform, i.e. the 900pm thick glass wafer, and the optical components, e.g. lens mold, frame mount, additional MLA wafer, are stacked direct in wafer scale on top of this wafer. After completing the mounting steps, the stack structure gets more stable and it is possible to conduct back grinding to significantly reduce the thickness of the glass wafer.

Although the disclosure has been described in terms of preferred embodiments as set forth above, it should be understood that these embodiments are illustrative only and that the claims are not limited to those embodiments. Those skilled in the art will be able to make modifications and alternatives to the described embodiments in view of the disclosure which are contemplated as falling within the scope of the appended claims. Each feature disclosed or illustrated in the present speci fication may be incorporated in any embodiment , whether alone or in any appropriate combination with any other feature disclosed or illustrated herein . In particular, one of ordinary skill in the art will understand that one or more of the features of the embodiments of the present disclosure described above with reference to the drawings may produce ef fects or provide advantages when used in isolation from one or more of the other features of the embodiments of the present disclosure and that di f ferent combinations of the features are possible other than the speci fic combinations of the features of the embodiments of the present disclosure described above .

The skilled person will understand that in the preceding description and appended claims , positional terms such as ' above ' , ' along' , ' side ' , etc . are made with reference to conceptual illustrations , such as those shown in the appended drawings . These terms are used for ease of reference but are not intended to be of limiting nature . These terms are therefore to be understood as referring to an obj ect when in an orientation as shown in the accompanying drawings .

Use of the term " comprising" when used in relation to a feature of an embodiment of the present disclosure does not exclude other features or steps . Use of the term " a" or " an" when used in relation to a feature of an embodiment of the present disclosure does not exclude the possibility that the embodiment may include a plurality of such features .

The use of reference signs in the claims should not be construed as limiting the scope of the claims . References

101 smartphone

102 multi-spectral ALS

103 multi-spectral ALS arrangement

104 camera

108 cover glass

110 , 310 , 510 , 810 monolithic semiconductor chip

111 optical detector region

112 , 312 , 512 , 812 detector subarray

120 housing

122 aperture

132 IR cut filter

140 optical axis of multi-spectral

ALS arrangement 103

142 FOV of multi-spectral

ALS arrangement 103

142a...1421 sector of FOV 142

150 optical axis of camera 104

152 FOV of camera 104

160 aperture member

160a aperture

161a the first microlens array

161b the second microlens array

162 ROB

164 frame member

166 , 366 , 566 , 866 , 966 optical filter

180 processing unit

360a, 560a, 860a the first aperture

360b, 560b, 860b the second aperture

360d, 560c, 860c the third aperture

860d the fourth aperture

367 , 567 , 867a, 867b optical glue 368 , 568 , 868 passivation layer

370a, 570a, 870a, 970a upper convex lens element

370b, 570b, 870b, 970b lower convex lens element

371a, 571a, 871a, 971a the first glass wafer 371b, 571b, 871b, 971b the second glass wafer

371c, 571c, 871c, 971c the third glass wafer

871d the fourth glass wafer

Claims

1. A multispectral optical sensor comprising:

- A monolithic semiconductor chip (510, 810) defining a plurality of subarrays (512, 812) of optical detector regions (511, 811) , each subarray comprising the same number and relative spatial arrangement of optical detector regions (511, 811) ;

- a plurality of lens arrangements, each of which is corresponding to one of the plurality of subarrays (512, 812) ;

- wherein each lens arrangement comprises an upper lens arrangement having an upper convex lens element (570a, 870a, 970a) , and a lower lens arrangement having a lower convex lens element (570b, 870b, 970b) and a bottom glass substrate (571c, 871d, 971c) mounted on the monolithic semiconductor chip (510, 810) through its bottom surface;

- wherein each lens arrangement further comprises an optical filter (566, 866, 966) provided on top surface of the bottom glass substrate (571c, 871d, 971c) , so that incident light from a scene passes through the optical filter (566, 866, 966) and then propagates in the bottom glass substrate (571c, 871d, 971c) along a direction towards a detector region (511, 811) of a subarray (512, 812) corresponding to the optical filter (566, 866, 966) .

2. The multispectral optical sensor according to claim 1, wherein each lens arrangement is aligned to focus the incident light onto a focal plane at the plane of the subarray (512, 812) of optical detector regions (511, 811) to form a focused image at the plane of the subarray (512, 812) of optical detector regions (511, 811) .

3. The multispectral optical sensor according to claim 1, wherein each lens arrangement is aligned to focus the incident light onto a focal plane adjacent the plane of the subarray (512, 812) of optical detector regions (511, 811) to form an out-of-focus image at the plane of the subarray (512, 812) of optical detector regions (511, 811) .

4. The multispectral optical sensor according to any of claims 1 to 3, the optical filter (566, 866, 966) is sandwiched between the lower convex lens element (570b, 870b, 970b) and the bottom glass substrate (571c, 871d, 971c) .

5. The multispectral optical sensor according to any of claims 1 to 3, the lens arrangement further comprises an additional glass substrate, which is placed between the lower convex lens element (570b, 870b, 970b) and the optical filter (566, 866, 966) .

6. The multispectral optical sensor according to any of the preceding claims, the upper lens arrangement further comprises a first glass substrate (571a, 871a, 971a) , and also a second glass substrate (571b, 871b, 971b) on which upper convex lens element (570a, 870a, 970a) are arranged.

7. The multispectral optical sensor according to any of the preceding claims, a passivation layer (568, 868) is arranged on top of the monolithic semiconductor chip (510, 810) .

8. The multispectral optical sensor according to any of the preceding claims, wherein the upper convex lens element (570a, 870a, 970a) /the lower convex lens element (570b, 870b, 970b) is a micro lens or a micro-Fresnel lens.

9 . The multispectral optical sensor according to any of the preceding claims , wherein the thickness of the bottom glass substrate ( 571c, 871d, 971c ) is 200-400 pm .

10 . A method of manufacturing a multispectral optical sensor, comprising the steps of : processing a structured optical filter layer on top surface of a bottom glass substrate/glass wafer, molding a lower layer of MLA on top of the structured optical filter layer, mounting a plurality of baf fle structures/ spacers onto the top surface of the bottom glass substrate/glass wafer ( 571c, 871d, 971c ) , and mounting an upper lens arrangement layer comprising an upper glass substrate/glass wafer and an upper layer of MLA to the bottom glass substrate/glass wafer, so that the upper layer of MLA and the bottom layer of MLA are faced to each other .

11 . The method of manufacturing a multispectral optical sensor according to claim 10 , further comprising : grinding the bottom glass substrate/glass wafer ( 571c, 871d, 971c ) to a predetermined thickness from its bottom surface to form a structure comprising plurality of lens arrangements .

12 . The method of manufacturing a multispectral optical sensor according to claim 11 , wherein the predetermined thickness is 200-400 pm .

13 . The method of manufacturing a multispectral optical sensor according to claim 11 or 12 , further comprising : dicing the structure to a plurality of separated lens arrangements and attach the lens arrangements to the monolithic semiconductor chip ( 510 , 810 ) .